Equipment with motors of all types will be provided with switches to control operation. However, only a fraction of such equipment is typically provided with kill switches for reasons of safety. For example, personnel are known to fall overboard from a powered motor boat: in the case of the pilot of a motor boat, especially with a lone pilot, the boat may continue to travel through water without an operator in the absence of an operational kill-switch arrangement. Further, such runaway boats have been known to seriously injure the operator of the boat in water since a runaway boat will have a tendency to circle and thus return to the place where the operator has fallen overboard. Such injuries are normally caused by the propeller of the boat cutting the operator in the water, or by the boat itself ramming the operator in the water.
In a completely different field—that of the health and wellness industry—gym equipment such as a treadmill, will be provided with on and off controls and will typically also have a kill switch associated with a lanyard for attachment to the user of a treadmill. In a recent incident, a 47-year-old CEO of a Silicon Valley company died of severe head trauma while exercising at a holiday resort in Mexico. It is well known that treadmill users are advised to use a safety key which stops the belt if one were to fall safety that are well worth reading, whether you own a treadmill or use one at the gym. It is notable that treadmills, in 2012, were the best-selling fitness machines in the United States, and it is reported that such sales accounted for about 25% of the industry's $77 billion in that year.
It is also well known that the use of power tools, for industrial and domestic use, such as power saws are susceptible to accidents. In fact, the woodworking industry has one of the highest accident rates in manufacturing, most of which are caused by contact with moving machinery. In the UK, this has accounted for 25% of all major industrial accidents in recent years, with several deaths in the woodworking industry. Intervention with rotating/reciprocating elements by operators is very often the cause of danger; whilst safety interlocks may be provided, such interlocks tend to slow down operation and are frequently circumvented, although kill switch arrangements per se (in a fashion similar to motor boats) are not provided. It will be appreciated that an operator might need to intervene and perform adjustments, such as adjusting settings, clearing blockages/misfeeds or removing dust/off-cuts and make sure they are trained to do this safely. In a study of 1000 accidents at woodworking machines, 4% occurred on narrow band sawing machines, where accidents often occurred while setting, cleaning, adjusting and maintaining a machine while a blade was still in motion, with an override of a safety function.
In order to prevent runaway motorised personal watercraft, devices such as a lanyard and an emergency shutoff device have been provided from the 1980s. For example, the watercraft could be a jet-ski and the lanyard switch ensemble includes a stop switch that protrudes from a handlebar arrangement and a claw-like lanyard lock plate engages the stop switch to allow an ignition system of an engine to operate. The lock plate includes a lanyard and a wrist strap for attaching the lock plate to an operator's wrist or a clip for attaching the lock plate to the operator's clothing so that if the operator falls off the watercraft during operation, the lock plate will be disengaged from the stop switch so as to kill the engine.
A lanyard lock plate can be a plastic mechanical clip, sometimes called a “latch-key”, a “key”, sometimes a “clip”, which slips onto the outside of an associated kill switch of the boat engine. The kill switch is typically located on the control or instrument panel of a boat and comprises a movable spring-loaded part which must be held in a certain position for the boat to run. The kill-switch key must be distinguished from a key used to operate a boat—or other motorised personal vehicle generally, since the key is operable to enable the vehicle to move and so, in one sense, could disengage a drive shaft, for example, although typically disables the ignition such that the engine is killed. Such a key can operate with a spring-biased element which works with the spring loaded portion of the switch and can be referred to as a latch-key—i.e. is distinguished from an ordinary metal turn-key, operable with other control systems with a boat etc. Should the operator fall overboard, the lanyard would become taught and would subsequently pull the latch-key from the switch, breaking the electric circuit of the engine ignition system, turning off, or “killing” the engine.
In U.S. Pat. No. 6,352,045 (Yamaha) a kill switch and engine control system is shown for a jet ski. U.S. Pat. No. 3,774,720 and U.S. Pat. No. 5,105,755 describe safety switch systems for marine vehicles in which the ignition system of an inboard motor or an outboard motor is linked to the extension of a ladder or the latching or unlatching of a gate, or a series of gates. However, such systems may be easily overridden by the simple pressing of a switch. Unfortunately, a simple switch override often results in the same type of accident because such overriding is accomplished quickly and easily.
U.S. Pat. No. 6,276,974 teaches of a safety system for a boat having a motor and an element movable between a latched and unlatched position for gaining access to the boat. The system includes a switch which is normally in a closed position. The switch is opened when the movable element travels to the unlatched position. At that point, the switch interrupts the ignition circuit of the motor. Thus, the movable element must be latched or travel to the latched position before the ignition circuit will permit the motor to run. However, this system also includes an override device for the switch, thus making the safety system liable to fail.
There are at least two marine wireless kill-cord systems on the market, which both rely on small battery-powered radio transmitters worn around the neck or securely clipped on. A continuous signal is sent to a control box mounted on the helm. As soon as contact with the remote fob is lost the engine is cut. They have been tested and seem to work well, but are not widely used as the market seems to be driven by the outboard and sports boat manufacturers in the US. The additional cost, complexity and fear of litigation in view of a possible failure to operate are all factors putting manufacturers off the replacement of the existing manual kill-cord, typically comprising a hard wire/cord system.
In May 2013, a speedboat in the waters near Padstow in Cornwall crashed, killing the pilot—a father—and his daughter. The pilot was not wearing a safety cord, which could have stopped the engine, the rest of their family were thrown out of their vessel. The United Kingdom's Marine Accident Investigation Branch (MAIB) said the pilot was not using the vessel's kill-cord correctly. In 2012, in a similar incident in the Camel estuary, the pilot and passenger of a rigid inflatable boat (RIB) were thrown into the water with the empty vessel running in circles “at high speed” before eventually running out of fuel. The pilot was not wearing a cord. At the Southampton International Boat Show in 2000, a young pilot died after he was thrown from a speedboat and subsequently run over by the boat as it circled in the water. Again, the pilot was not wearing a cord.
There are many owners of motorised pleasure craft who have craft with significant levels of power and capable of enabling boats to reach speeds of 50 mph (80 km/h) and above relatively straightforwardly. A very high-powered boat can have a quicker response time than many sports cars, since the propellers of an outboard or outdrive cause the thrust to be changed rapidly, without the feedback that a motorist will experience. Just as a car might flip on a sharp bend, it's easy to be thrown out of a boat at speed. A properly fastened kill-cord would cut a boat's engine if the pilot fails out of a motor boat.
Presently, there is no legal requirement for a kill-cord to be fitted to any kind of boat in the Recreational Craft Directive (RCD), which is the safety standard to which all boats in the EU have to conform. There is however a section in the Inland Waters Small Passenger Boat Code which states that, “All inflatable boats, those fitted with buoyant collar and open boats able to achieve planing speed, should, if they have remote throttle controls, be fitted with a kill-cord, which must be used at all times”. Nonetheless, despite the lack of boatbuilding legislation, most outboard engine manufacturers do supply a kill-cord system with every engine sold and most manufacturers of sports boats, rigid inflatable boats (RIBs), including those powered by inboard engines, choose to fit them. This is believed to stem from the threat of litigation, especially in the United States. One engine manufacturer has offered complimentary Royal Yachting Association tuition with the purchase of one of their outboards from 50 hp upwards, which training involves use of kill-cords. Notwithstanding the lack of legal obligation for leisure boat owners to wear a kill-cord fitted to the boats, there may be a clause in an insurance policy which mandates the correct use of a kill-cord. Commercial operators are typically governed by a code of practice which requires the use of a kill-cord when fitted.
Various alternative approaches have been considered, such as, the provision of pressure sensors on a steering wheel or helm seat, which sense whether the helm is occupied or not and that kill an engine if not depressed for a certain period of time, or a GPS device attached to the helmsman which cuts out when outside a certain range of the boat. Other suggestions are optical or thermal sensors similar to a burglar alarm. Many prior art devices lack essential simplicity and low cost of a lanyard system, they have to be either installed at the factory or inconveniently retro-fitted by a skilled electrician—noting that it can be extremely difficult to adapt hard-wired systems to the diverse range of boat instrument panels and wiring configurations. Some boat builders favour wireless kill-cords but they are restricted by what is warranted by the engine suppliers and many inboard engines used in small open boats have no warranted kill-cord option.
Safety devices of the type discussed above, be they a lanyard or transmitter, can be worn by the pilot operator of a boat by placement on a lanyard about the neck of the pilot or on a strap which may fit around the wrist or ankle of the pilot, the torso of a user of gym equipment or a lanyard associated with a power-tool. In the marine environment, in order to ameliorate the issue of having a tether attached to the body, some life-jackets or buoyancy aids can be provided with kill-cord attachment loops on both sides. In the agricultural and building trades, safety devices are often circumvented, in part arising from the macho cultures of such trades and, in part, arising from the simple inconvenience of having a tether attached to one's body. It is notable that fear of an accident will not provide a guarantee that a safety tether will be attached.
Marine accidents where a boat or the propeller of a boat has struck an operator in the water have occurred in the past with devastating consequences. Complacency with regard to safety among powerboat users is believed by some to be at the root of the problem. Whilst fatal injuries from treadmills are rare—between 2003 and 2012, there were 30 deaths associated with treadmills (an average of three deaths per year) according to a Consumer Product Safety Commission based in the US, other injuries—such as ankle sprains or skinned knees—are more common (in 2014, there were about 24,400 injuries in the US associated with treadmills that required a visit to a hospital accident and emergency department).